What to do with your head during meditation?
Some people equate a bowed head
with introspection and stillness.

The trouble with this posture is that
it puts an unhealthy strain on the neck and spine,
especially if you are meditating for an extended period of time.

Research has also indicated that this position
inhibits a positive attitude and sense of well being,
while promoting worry, fear, and negative expectations.

This is probably why many long time meditators
choose to face forward or upward instead of bowing.

The tradition of bowing for prayer or introspection
is probably an attempt at a humble posture.

Bowing at the waist or kneeling
or bowing your head to the ground
while lying face down
all support this goal
without the unhealthy contortion of the neck.